German astrophysicist Reinhard Genzel, 73, takes the stage. He then begins his lecture in the most unexpected way: “What’s the point of talking about black holes if all the Hollywood producers already know what they are? Going into them is easy, but once you do… ooooh.” The audience — made up of a couple of hundred professors and students from 20 countries — is taken aback.
Genzel — who was born in the town of Bad Homburg — acts like a friendly guy who just happens to be passing by. But he’s actually one of the scientists who discovered the central object of our galaxy: Sagittarius A*, a colossal black hole, with a mass equivalent to four million stars like the Sun. The director of the Max Planck Institute for Extraterrestrial Physics speaks with passion and a sense of humor about his discoveries, for which he shared the 2020 Nobel Prize in Physics, along with theorist Roger Penrose and experimental astronomer Andrea Ghez.
In early November, Genzel attended the Hong Kong Laureate Forum, which awards the Shaw Prize (often described as the Chinese Nobel Prize). He was delivering a vibrant lecture at the city’s Science Park, as a guest of the same forum that recognized his discovery 12 years before the Swedish Academy did. After his talk, he answered some questions from EL PAÍS.
Question. What’s the biggest implication of discovering something like Sagittarius A*, the black hole at the center of the Milky Way?
Answer. Many people are used to understanding the universe as a realm of surprise and wonder that borders on the irrational. Things happen, [such as] explosions that leave you in a state of amazement. What I do, on the other hand, is use astronomical techniques to do physics remotely. It would be much better to fly to a black hole and do the studies there, although we would have to consider the safety risks of getting too close. In any case, this is impossible. So, what we do instead is good theoretical physics and good experimental physics. We combine them to arrive at the truth.
I think humanity has lost a bit of its appreciation for the truth. And I think that’s partly because of social media.
Q. Why?
A. There are truths that can’t be explained in three seconds. Understanding them, even minimally, can take an hour. And if you don’t want to accept what I tell you as the truth, but instead wish to form your own opinion, you need six months of study. This also applies to politics: understanding the war between Hamas and Israel requires an investment of time.
I’m sure young people can find it stimulating to dedicate time to understanding something that interests them, so that no one comes along and tells them a three-minute, simplified version.
Q. Do you really think they’ll do this?
A. I’m sure of it. One-minute videos will never give you the truth. It has taken humanity 4,000 years to understand the solar system, and we’ve achieved this thanks to the contributions of many cultures and civilizations. Isn’t that a wonderful accomplishment?
Q. You’ve said that you don’t care to know what’s inside a black hole, because it’s impossible to find out. Even so, do you never ask yourself that question?
A. In my life, I’ve learned not to be interested in — and not to ask questions about — things that I know there are no answers to. I would love to know what happens inside a black hole, what happens when you cross its boundary, but I know I’ll never get the answer. So, let’s not worry about what we can’t know. That’s been a bit of a motto for me in life.
Q. Does that way of thinking still leave room for unexpected discoveries?
A. Of course it does. For that reason, after a major discovery, you must continue refining it. And often what you thought was one thing turns out to be something else entirely. Now, can science provide the ultimate truth? That’s a question for philosophers. My answer is that, if you’ve been able to build a car or an airplane with what you know, then there’s some truth to it.
Q. What do we still need to know?
A. Just five years ago, we thought we knew how black holes formed. We know, for example, that their mass doubles every 400 million years. But then, we launched the James Webb Space Telescope. And it turns out that there are, in fact, enormous black holes that appeared relatively soon after the birth of the universe, following the Big Bang. [That’s] something we haven’t understood and solving it won’t take us years, but decades.
Q. The forum you’re attending here in Hong Kong is more focused on geopolitics than science. How do you see the global situation?
A. I think Europe is wise enough to know that, if we stick together, we can survive, and we can even continue doing science at the highest level. [But] if we’re unlucky enough to have the Russians defeat Ukraine and invade Poland or the Baltic states, then there will be another world war.
Q. Does the United States under Donald Trump further strain the situation?
A. This president and his cronies are destroying everything that made America great. My eldest daughter still lives in the United States, where I spent a good part of my career. I had a green card, but it was revoked shortly after Trump won the election. I can still visit her as a tourist, but I think that, if I keep saying things like this, one day they’ll stop me at the border and throw me in jail. But we mustn’t stay silent. This is something that I learned from the history of Germany, my country, after World War II. Why didn’t we say something when we still had the chance?
Q. What role does China play in the current geopolitical context?
A. I have very good Chinese friends who tell me that their country will never reach Gleichschaltung — the German term that defines the control of the individual [that took place] under Nazism. If this is the case, if China allows some freedom, I think it’s legitimate to collaborate with them. I say, let’s try it, let’s give them the benefit of the doubt, since they seem to respect thought and culture, to the extent that they don’t turn their backs on people who come from different political systems.
Q. In your lecture, you said that curiosity is the greatest human quality. What do you think is the greatest question we should direct that curiosity toward?
A. Impossible to know; we’ll discover it along the way. Right now, I’m thinking about my second grandson, who is a year-and-a-half-old. He sits down to play and inspects the pieces of a puzzle, turning them over until he sees how they fit together. And that’s how it happens; that’s how we apes became more intelligent than the rest. We weren’t stronger than them, but we thought more and better
Today, our ability to reason also depends on certain skills, such as mathematics. Obviously, the question now is how important artificial intelligence will be. I’m cautiously pessimistic that it can make discoveries at a human level, but the best thing is to see where it takes us. Let’s be positive.
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